The subject matter disclosed herein relates to the art of wind turbines and, more particularly, to a method and system for replacing a wind turbine blade.
Wind generators convert energy provided by air currents into electricity. The air currents rotate large rotor blades or propellers that are mounted in nacelles at the top of a tower. The blades spin a rotor relative to a stator to generate an electrical current. The rate of rotation is controlled by varying blade pitch as well as through the use of various braking systems. During high wind conditions, the blade pitch is adjusted to spill wind energy in order to limit rotational speed. Occasionally, the braking system is employed to further prevent the blades from achieving high rotational speeds. During low wind conditions, the blade pitch is adjusted in order to capture as much wind energy as possible.
Over time, the wind generators require maintenance. Debris, hailstones and the like oftentimes impact the blades and cause damage. Replacing a worn or damaged blade generally requires the presence of one or more large ground or sea based cranes. The large cranes are used to retain and lower the blade to a surface such as the ground or a ships deck. In some cases, replacing a blade necessitates that others of the blades be moved to an off balance position. That is, a brake system is activated to position the blade being replaced in a position that is horizontal to ground. In such a case, the others of the blades are off-balance imparting forces to the braking system. In other cases, the blade is placed in a position perpendicular to ground and lowered. In such cases, multiple crews are required to rotate the blade to prevent contact between the surface and a tip portion of the blade that may result in damage.